A member of the Afghan security forces investigates the site of yesterday's suicide bomb attack in Kabul, Afghanistan, November 21, 2018.
(Reuters)

Afghan authorities were struggling on Wednesday to identify the group behind a suicide bomb attack that killed at least 55 people and wounded 95 at a gathering of religious scholars in Kabul after the Taliban denied any responsibility and Daesh, which has claimed most suicide attacks in Kabul this year, issued no statement.

The victims included religious delegates from various parts of the country, invited by the Afghan Ulema Council to celebrate the birth anniversary of Prophet Muhammad on Tuesday.

President Ashraf Ghani declared Wednesday a national day of mourning for the victims of the attack, which he described as an "unforgivable crime."

Without knowing who was behind the attack, it was unclear whether the aim was to undermine Ghani's government, or whether it was part of a strategy to keep the pressure on his government and its Western allies while they pursued talks with the Taliban, to end the 17-year-long war.

"As of now we don't know which militant outfit could be behind the attack. Investigations are at a preliminary stage," said a senior security official who was at the blast site on Wednesday to collect forensic evidence.

The council, the country's largest religious organisation, gathered scholars from the Sunni sect, but it was uncertain whether the attack could have had a sectarian dimension.

Officials not ruling out Taliban role

Though Sunni themselves, Taliban and Daesh have targeted religious scholars aligned with the Afghan government in the past.

This time, the Taliban quickly denied responsibility and condemned the attack on religious preachers and scholars, but investigators in Kabul said the group's involvement cannot be ruled out.

The toll from Tuesday's attack could rise as most of the 80 wounded had severe wounds, hospital and government officials said.

On Wednesday, two rockets hit Ghazni city where the top US general leading the NATO-led force in Afghanistan, Scott Miller, was meeting the provincial governor and senior officials at the governor's compound, said Ahmad Khan Serat, a spokesman for Ghazni police.

"Gen Miller was not hurt in the rocket attack," Serat said, adding that two rockets fell on a money exchange market, about 200 metres from the governor's compound in the central strategic province.

Debra Richardson, a spokesperson for the NATO-led Resolute Support mission, said Miller was in Ghazni province for a meeting with Afghan military leadership to discuss security.

"While he was there, the Taliban indiscriminately launched indirect fire but we do not believe General Miller was the target," Richardson said in a statement.

No group has claimed responsibility for the rocket attack in Ghazni.

In October, Miller survived an attack by a Taliban fighter in the southern province of Kandahar in which a legendary Afghan police general and the local intelligence chief were killed, and two Americans were wounded.

US-Taliban talks

Last week, Taliban leaders met US special envoy Zalmay Khalilzad at their political headquarters in Qatar in an effort to pave the way for peace talks. The three-day meeting was the second in the past month.

Khalilzad has declared a deadline of April 20, the day of Afghanistan's presidential election, to end the war, but the country's security situation has worsened since NATO formally ended combat operations in 2014.